Objective: The aim of this study was to evaluate the use of a convolutional neural network (CNN) system for predicting C-shaped canals in mandibular second molars on panoramic radiographs. Methods: Panoramic and cone beam CT (CBCT) images obtained from June 2018 to May 2020 were screened and 1020 patients were selected. Our dataset of 2040 sound mandibular second molars comprised 887 C-shaped canals and 1153 non-C-shaped canals. To confirm the presence of a C-shaped canal, CBCT images were analyzed by a radiologist and set as the gold standard. A CNN-based deep-learning model for predicting C-shaped canals was built using Xception. The training and test sets were set to 80 to 20%, respectively. Diagnostic performance was evaluated using accuracy, sensitivity, specificity, and precision. Receiver-operating characteristics (ROC) curves were drawn, and the area under the curve (AUC) values were calculated. Further, gradient-weighted class activation maps (Grad-CAM) were generated to localize the anatomy that contributed to the predictions. Results: The accuracy, sensitivity, specificity, and precision of the CNN model were 95.1, 92.7, 97.0, and 95.9%, respectively. Grad-CAM analysis showed that the CNN model mainly identified root canal shapes converging into the apex to predict the C-shaped canals, while the root furcation was predominantly used for predicting the non-C-shaped canals. Conclusions: The deep-learning system had significant accuracy in predicting C-shaped canals of mandibular second molars on panoramic radiographs.
The number of industrial accidents has been recorded by construction cranes for a high proportion compared to other machines on construction sites. For this reason the technology for preventing collision between salvages and obstacles is strongly demanded. In this study, we propose an intelligent safety management method based on a rotational obstacle detection that detects obstacles around a crane by learning a private dataset acquired in an environment similar to an actual construction site. The rotational obstacle detection model of the proposed method is designed to more accurately predict obstacles around a crane using RGB video sequences images from the multi-domain dataset. It is composed of the real-time models for object detection, one of the typical one-stage detectors, and the self attention distillation (SAD) method. In the experimental results, its performance of accuracy over than 70% mAP. This study can be applied not only to cranes but also to other machines for safety monitoring systems on various domain fields.
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